Flexible implants are usually made of polyhydroxyethyl methacrylate (pHEMA) or of a silicone-based material presenting the essential feature that since the optical portion of such an implant is made out of such a flexible material, the implant and in particular its optical portion can be folded so as to reduce its transverse dimensions and thus enable the implant to be inserted into the eye through an incision made in the cornea, said incision being very small in size, typically about 3 millimeters (mm).
Such flexible implants are particularly advantageous in that novel techniques for removing the natural lens now require an incision to be made in the lens that is of small size only, about 3 mm when using the technique of phacoemulsifcation.
Nevertheless, folding the implant which is constituted by a substantially circular optical portion and by a haptic portion, presents certain difficulties, in particular because of the small dimensions of an intraocular implant where the diameter of the optical portion is typically no more than 6 mm, given the nature of the material constituting the implant.
In order to enable the implant to be folded or rolled up prior to being inserted in the eye, various types of flexible implant injector have already been proposed that incorporate a folder unit for the implant.
The term “folding” the implant should be understood as covering any mechanical operation enabling the shape of the implant to be modified elastically, and in particular the shape of its optical portion, so as to reduce the transverse size of the implant, i.e. in a direction that is orthogonal to the diameter of the optical portion containing the haptic elements of the implant. This can comprise merely folding about a diameter of the optical portion, or folding that is more complex about axes that are parallel to said diameter, or indeed rolling up about an axis parallel to said diameter.
It will be understood that once the implant has been folded, it suffices to place a cannula in the incision in the eye, said cannula extending the folder unit, and then to push the implant while it is in its folded shape through the cannula and into the inside of the eye.
Document WO 95/13022 describes a flexible implant injector comprising a folder unit which is constituted firstly by a folder chamber having a curved folder wall and two parallel walls, and secondly by a pusher acting on the proximal edge of the optical portion of the implant in a direction orthogonal to the folder wall, so that progressive displacement of the pusher causes the implant to be folded or rolled up.
Nevertheless, it has been found that that type unit for folding or rolling up an implant is poorly adapted, particularly when the implant has certain types of haptic portion. It will be understood that the haptic portion which is usually constituted by two distinct elements needs to be folded or rolled up in the same direction as the optical portion. Unfortunately, the haptic portion is of dimensions that are small relative to those of the optical portion and as a result it has weaker mechanical strength properties which make folding the haptic portion very difficult.
In addition, it is awkward to put the implant into the folder chamber of a known folder module, and proper positioning of the haptic portions is random.